drawing bounding box on the largest object

hi, now i have a piece of code that can draw bounding box around a square in an image. but the problem is that when i load an image with two squares (1 large, 1 small), the code will only draw the bounding box around the smaller square but not the larger 1. how i can change the code so that the larger square will have a bounding box around it.

thank you very much for your helpful replies